Select Committee on Environment, Food and Rural Affairs Minutes of Evidence

Examination of Witnesses (Questions 135 - 139)




  135. Professor King, and Dr Grenfell and Professor Woolhouse. Professor King, you are a sort of deus ex machina of the Government, are you not, you sort of keep popping up from time to time when there appears to be either something going wrong or a crisis or a corrective to be applied, so we thought it was about time you popped up again, so that is why we invited you. We want to talk obviously about foot and mouth disease, though there is the issue of BSE in sheep, the rather recent issue. You have given us some charts. Jim Scudamore appeared before us last week, and quite a large number of the pages in this were ones he circulated and talked to last week, so I am anxious that we should not go over the same ground twice, but if there are some preliminary things you would like to say perhaps you would like to do so? Could I say that this room is a sort of cavernous place in which the acoustics are not easy for anybody, so we all try to shout a little bit, and I am sorry about that but I did not design it.
  (Professor King) The FMD story document that I have circulated I think will be materially different from the one that Jim Scudamore would have circulated, for the simple reason that this one dwells on the scientific input that my group had throughout the FMD outbreak, and has to the present time. And, of course, what it stresses is the importance of the scientific modelling that was done to project forward from any point during the outbreak as to what the outcome would be given various control scenarios. So I think that would be the difference in emphasis.

  136. That is helpful, and you will no doubt refer to it from time to time during your remarks, but you do not particularly want to sort of make a presentation based on it?
  (Professor King) The expectation was not to make a presentation but rather to respond to questions.

  137. That is a happy coincidence between your view and my view. Could we start by just looking at where we are on sheep, brains of, and all that. You were asked if you could find out what had gone wrong and where we are going on this issue. You will not need us to say that it is a bit of a sword of Damocles hanging over the industry, lots of rumours and belief that if BSE were seen to be present in sheep brains, screened by scrapie, we would be into the universal slaughter of the flock, though the Minister put that one to rest yesterday, I think. But it would be helpful to know, are you yet able to find out what actually went wrong in the famous experiment, and, I think, more importantly, where are we heading in the experiment on the possible existence of BSE in the modern day sheep flock?
  (Professor King) Can I make first two preliminary statements, and the first one would be to underline what the Food Standards Agency is currently saying, though I certainly believe that they are saying this with good reason, and that is that there is no reason to deter people from eating lamb, British lamb. The second point to make is that the test that is under scrutiny at the moment was a test on sheep brain from a pool that was collected over the period 1990-92 and is therefore not particularly relevant to sheep in the field today. And so, whatever the outcome of that test, meat and bonemeal was terminated in 1996 as feedstock, finally, and so the possibility of BSE in sheep today is a question that hangs over, whatever the results of that test. Your specific question about how that came to be, that a test lasting such a long period of time and costing quite a lot of money should apparently have been done of a brain pool that was cattle brain rather than sheep brain. There is an audit, as I am sure you are aware, currently being conducted, it was requested by DEFRA, it is being done by an independent firm of consultants; we had anticipated the results of that audit round about the beginning of this week, and I believe it has been delayed, so I have not yet seen the result. And there is a second audit that will take longer, that is being conducted by UKAS, and I expect that that will go into things in much more detail. Until either of those audits is out, particularly the first, I would not like to comment on whether or not the samples were incorrectly drawn, as some would say, or whether, in fact, the brain pool that was being examined was, in fact, cattle brain.

  138. As we are going to get the results of those audits, I do not think there is much profit in trying to pursue that one now, especially as we have the Secretary of State in front of us at this time next week, so that if we have some results we will no doubt want to come back to that. Can you just look forward though at the same issue, because, as you said, quite rightly, what really matters is what is the state of the current flock; we know that the Department wishes to accelerate the programme of developing a scrapie-resistant national flock, and part of that is included in the Bill which we will debate on Monday. But where are we on the development of more effective, rapid tests on live animals, to be able to distinguish between scrapie and BSE, because that is at the heart of the present debate, is it not?
  (Professor King) The reason for the long period in the tests at the Institute of Animal Health in Edinburgh was because they were using the mice assay, which I think everyone regards as the gold standard for distinguishing BSE prion from scrapie prion. And what we are now investigating and pursuing with vigour is the molecular tests, the tests based on biochemical analysis, which can be conducted in 24 to 48 hours on a given animal. The western blot technique has already been used with quite a number of tests on scrapie sheep at the VLA, I believe the number is in the region of 480, but this is a moving target; as we speak, further experiments are being conducted. And, using this technique, so far, all of the sheep with scrapie symptoms have shown scrapie prion and not BSE prion. And this is actually a significant result, because the BSE in sheep, when infected in the laboratory, the sheep show the symptoms of scrapie; so if we are going to find BSE in sheep it is most likely to appear in those sheep which are showing scrapie symptoms.

  139. They key is, when do you have sufficient results, by whatever test, to be able to declare that, according to any reasonable analysis, the flock is BSE-free? Jim Scudamore told us, on several occasions, that as far as foot and mouth disease we had not merely to be disease-free but we had to be virus-free before we could declare ourselves to have got shot of the disease, and clearly the samples you have to take to make that credible are considerable. What do we need to demonstrate for you to be able to sit there, absolutely confidently, and say, "I can now say, with absolute certainty, insofar as one can in anything in this business, that there is no BSE in our national sheep flock"?
  (Professor King) I am going to reply with a statistical answer. The normal position of uncertainty that we are prepared to live with is a 95 per cent confidence limit, and, I have mentioned a number of about 480 sheep being tested; if we randomly tested 300 sheep in the sheep population and found no BSE, we would have a 95 per cent confidence that the incidence is less than 1 per cent, but, of course, 1 per cent of 40 million sheep is a large number. So what we need to do is bring that down to 0.001 per cent before we would bring it down to a number small enough that we would be assured that we really did not have BSE in the sheep population. But you will understand that we will never be able to do it for a sufficient number of sheep to have 100 per cent certainty, unless we tested every sheep going into the food chain.

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